1. Technical Field
The present invention relates to an electronic device and a method of manufacturing the electronic device.
2. Related Art
A thin-film circuit device has a thin-film circuit layer including a semiconductor element and the like on the surface of a substrate. A single-crystal silicon wafer, a quartz glass substrate, a heat resistant glass substrate, a resin film, or the like is used as the substrate. An appropriate material is selected for a substrate depending on performances and functions of a required thin-film circuit device. In a thin-film circuit device in which the resin film is used for the substrate among them, the substrate itself is thin and flexible. Therefore, if the resin film is used for the substrate, a thin-film circuit device which is lightweight and has flexibility can be provided.
As a method of manufacturing the thin-film circuit device in which the resin film is used for the substrate, the following methods have been proposed. That is, a method of obtaining a thin-film circuit layer by laminating a semiconductor layer, a dielectric layer, a metal layer and the like in order on the resin film, a method of separating a thin-film circuit layer which has been previously formed on the surface of a heat resistant substrate, such as a glass substrate, from the substrate and bonding the thin-film circuit layer onto the resin film through an adhesive, and the like, have been proposed.
In particular, as a method of manufacturing a display module called an electronic paper which has been recently focused on as a novel electronic device, specifically, a method in which a microcapsule-type electrophoretic material and a thin-film circuit layer are combined on the resin film so as to provide a flexible electrophoretic display having high performance has been proposed.
When the thin-film circuit layer provided on the resin film is used as a driving circuit for a display element, it is necessary that a substrate for external connection (hereinafter, also referred to as “connection substrate” simply) be bonded to the thin-film circuit layer such that a power, a signal, and the like can be externally input to the thin-film circuit layer.
In this case, when the thin-film circuit layer and the connection substrate are bonded to each other, an anisotropic conductive material (for example, an Anisotropic Conductive Film (ACF), an Anisotropic Conductive Paste (ACP), or the like) is used in many cases. The thin-film circuit layer and the connection substrate are electrically connected to each other with conductive particles contained in the anisotropic conductive material (for example, see, JP-A-2009-75232).
To be more specific, the surface of a circuit substrate formed with a resin film and a surface of a connection substrate are opposed to each other. Further, an anisotropic conductive material containing conductive particles is interposed between a terminal portion of a thin-film circuit layer and a wiring layer. The thin-film circuit layer is provided on the surface of the circuit substrate. The wiring layer is provided on the surface of the connection substrate. Then, the circuit substrate and the connection substrate are positioned on a stage in a state where the anisotropic conductive material is sandwiched therebetween. Further, a portion on which the terminal portion and the wiring layer are overlapped with each other is pressurized and heated. With this, the terminal portion and the wiring layer are electrically connected to each other through the conductive particles.
However, in an existing connection method, the conductive particles are strongly pressed against the terminal portion by the pressurization when the terminal portion and the wiring layer are connected to each other. The terminal portion is formed by a thin film such as Indium Tin Oxide (ITO), for example. Therefore, there has been a risk that the terminal portion is damaged if the conductive particles are strongly pressed against the terminal portion.